where can I find the DNS name associated to the listener of an Availability Group?

Question

I have an availability group that has a listener.

The listener is called SQLPROD as you can see on the picture below. It uses port 1433

When I run the following script:

ALTER AVAILABILITY GROUP [SQLPROD_AG]
    ADD LISTENER 'SQLPROD' (WITH IP (('200.1.1.199', '255.255.254.0')));

I get this error message (when it already exists):

Msg 19477, Level 16, State 48, Line 4 The availability group 'SQLPROD_AG' already has a listener with DNS name 'SQLPROD_AG_SQLPROD'. Availability groups can have only one listener. Use the existing listener, or drop the existing listener and create a new one.

using the Always On Availability Groups Catalog Views I haven't found anything revealing:

select * from sys.dm_hadr_auto_page_repair  
select * from sys.dm_hadr_cluster_networks
select * from sys.dm_hadr_availability_group_states 
select * from sys.dm_hadr_database_replica_cluster_states
select * from sys.dm_hadr_availability_replica_cluster_nodes    
select * from sys.dm_hadr_database_replica_states
select * from sys.dm_hadr_availability_replica_cluster_states   
select * from sys.dm_hadr_instance_node_map
select * from sys.dm_hadr_availability_replica_states   
select * from sys.dm_hadr_name_id_map
select * from sys.dm_hadr_cluster   
select * from sys.dm_tcp_listener_states
select * from sys.dm_hadr_cluster_members   


select * from sys.availability_databases_cluster    
select * from sys.availability_groups_cluster
select * from sys.availability_group_listener_ip_addresses  
select * from sys.availability_read_only_routing_lists
select * from sys.availability_group_listeners  
select * from sys.availability_replicas
select * from sys.availability_groups

All seems to be fine:

when I use powershell, the following commands:

Import-Module FailoverClusters  
cls
Get-ClusterResource 

Where can I find where the name SQLPROD_AG_SQLPROD is? Can I change this name?

Answer 1

The message that is returned is not accurate as it is referring to the name that it will give the network name resource (SQLPROD_AG_SQLPROD), and it is labelled incorrectly as the DNS name. You can see that the network name resource in your AG is named SQLPROD_AG_SQLPROD, and that is what it's referring to.

It really should say something like, "The availability group 'SQLPROD_AG' already has a listener with a network name resource of 'SQLPROD_AG_SQLPROD'." When the listener is created, the associated network name resource is created with a name according to the following syntax:

<Availability Group Name>_<DNS name>

Since a resource with that name already exists, it can't create it.

Also, underscores aren't allowed in DNS names, so the name given in the error message is obviously not a DNS name.

To see the DNS name associated with the listener, you can use SQL Server Management Studio and view the properties of the listener, or use Failover Cluster Administrator and view the properties of the network name.

The following PowerShell command will return the names and DNS names of all network name resources that are not core cluster resources.

Get-ClusterResource | Where-Object {$_.isCoreResource -eq $false -and $_.ResourceType -eq "Network Name" } | Get-ClusterParameter | Where-Object { $_.Name -eq "DnsName" } | Select ClusterObject, Value

If you want to filter by a specific AG name, you would use Where-Object {$_.OwnerGroup -eq "SQLPROD_AG" -and $_.ResourceType -eq "Network Name' } for the first WHERE clause.

With T-SQL, you can get this from the AG-related views. To list all:

select ag.name, agl.dns_name from sys.availability_group_listeners agl
join sys.availability_groups ag ON ag.group_id = agl.group_id

To list only the one for SQLPROD_AG, you would just need to add a WHERE clause:

WHERE ag.name = 'SQLPROD_AG'

If you're wanting to use a different DNS name for the listener, you have to drop the current listener and create a new one.

ALTER AVAILABILITY GROUP SQLPROD_AG REMOVE LISTENER 'SQLPROD'

See Remove an availability group listener.